7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-0846

CVE-2026-0846: Arbitrary File Read via Absolute Path Input in nltk.util.filestring()

A vulnerability in the filestring() function of the nltk.util module in nltk version 3.9.2 allows arbitrary file read due to improper validation of input paths. The function directly opens files specified by user input without sanitization, enabling attackers to access sensitive system files by providing absolute paths or traversal paths. This vulnerability can be exploited locally or remotely, particularly in scenarios where the function is used in web APIs or other interfaces that accept user-supplied input.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-0846

CVE-2026-0846:

7.5

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

SSVC / BOD 26-04 ↗

Exploitation pocAutomatable YesTech Impact Partial

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Package Name	Ecosystem	Vulnerable Versions	First Patched Version
nltk	pip	< 3.9.3	3.9.3

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability exists in the filestring function located in the nltk/util.py file. The analysis of the commit patch clearly shows that the original function directly used the open() call on a user-provided string f without any sanitization or path validation. This is a classic path traversal vulnerability. The provided patch modifies the filestring function to add an optional allowed_dir argument. When this argument is provided, the function performs checks to ensure that the requested file path is within the allowed directory, thus preventing path traversal. However, for backward compatibility, if allowed_dir is not specified, the function falls back to the old, insecure behavior of opening the path directly. Therefore, any application using nltk.util.filestring(user_input) without the allowed_dir parameter is vulnerable. The vulnerable function signature that would appear in a runtime profile is filestring.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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